1. Field of Invention
The invention relates to a driving control device, and more particularly to a fan system and a driving control device of a motor.
2. Related Art
The heat dissipating problem of an electronic device is more and more important nowadays due to the increase of the data processing information and the processing speed of the electronic device. In addition, the integrated process had become advanced so that more electronic elements can be contained in the same electronic device. The major heat dissipating method is to provide a fan in or on the electronic device for inducing the air convection so as to achieve the heat dissipating effect.
Accordingly, the thermal controlled fan, which can sense the environment temperature by a sensing element and adjusts the rotation speed thereof in accordance with the temperature, is disclosed. The sensing element can be a thermal resistor, which is sensitive to the temperature variation and can change its resistance value according to different temperatures. In addition, the thermal resistors include a positive temperature coefficient (PTC) resistor and a negative temperature coefficient (NTC) resistor. The resistance of the PTC resistor increases and that of the NTC resistor decreases when the temperature increases. Now, the thermal resistor is widely applied as the sensing element in the electronic device for facilitating the control and compensation of other circuits in the electronic device.
FIG. 1A is a schematic block diagram of a conventional fan system 1, and FIG. 1B is a schematic circuit diagram of the fan system 1 in FIG. 1A. Referring to FIGS. 1A and 1B, the fan system 1 includes a temperature sensing circuit 11, a driving circuit 12 and a fan 13. The temperature sensing circuit 11 senses an environment temperature for generating a sensing signal S11. The driving circuit 12 receives the sensing signal S11 and transfers it into a driving signal S12 so as to drive the fan 13.
The temperature sensing circuit 11 has a resistor R and a thermal resistor RT, which are connected in series so as to divide the operating voltage VCC. The thermal resistor RT generates a resistance in accordance with the environment temperature. The variation of the resistance causes a node voltage value V1 with variation between the thermal resistor RT and the resistor R so as to output the temperature sensing signal S11. The driving circuit 12, which is a chip or a microprocessor, receives the temperature sensing signal S11 and transfers it into the driving signal S12 so as to drive the motor 131 of the fan 13.
As mentioned above, the driving circuit 12 of the conventional fan system 1 must receive and transfer the temperature sensing signal S11 into the driving signal S12 with a high voltage level or a high current level so as to drive the fan 13.
In order to adjust the driving signal S12 in accordance with the temperature variation immediately, the chip of the present driving circuit 12 is usually integrated in a chip with multiple functions and the chip is expensive. In this way, the expensive chip also raises the cost of the whole electronic system. The expensive chip thus limits its application fields. Therefore, it is an important subject to provide a driving control device having low cost and suitable for more application fields.